U.S. patent number 5,360,062 [Application Number 07/793,453] was granted by the patent office on 1994-11-01 for well tubing and tubing collar therefor.
This patent grant is currently assigned to H. Wade White. Invention is credited to H. Wade White.
United States Patent |
5,360,062 |
White |
November 1, 1994 |
Well tubing and tubing collar therefor
Abstract
A well tubing includes an insert nipple for receiving a
hold-down projection of an insert pump. The tubing includes a
tubing collar threadingly interconnecting the upper end of the
insert nipple with the next upper tubing section. The tubing collar
includes a tapered inner bore which becomes progressively larger in
cross-section in the upward direction to provide, around the
outside of the hold-down projection, a space of gradually enlarged
volume for receiving debris as the insert pump is lifted from the
well tubing, thereby preventing the pump from becoming stuck.
Inventors: |
White; H. Wade (Carlsbad,
NM) |
Assignee: |
White; H. Wade (Carlsbad,
NM)
|
Family
ID: |
25159950 |
Appl.
No.: |
07/793,453 |
Filed: |
November 18, 1991 |
Current U.S.
Class: |
166/105;
166/242.6 |
Current CPC
Class: |
E21B
17/02 (20130101); E21B 17/04 (20130101); E21B
23/02 (20130101) |
Current International
Class: |
E21B
17/02 (20060101); E21B 23/00 (20060101); E21B
23/02 (20060101); E21B 17/04 (20060101); E21B
043/00 () |
Field of
Search: |
;166/68,105,108,250,260,297,105.5 ;417/435,456,554,513 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Britts; Ramon S.
Assistant Examiner: Tsay; Frank S.
Attorney, Agent or Firm: Burns, Doane, Swecker &
Mathis
Claims
What is claimed is:
1. A well tubing adapted to receive an insert pump, said tubing
comprised of a plurality of tubing sections interconnected by
tubing collars, said tubing collars having internal threading
connected to external threading on successively arranged tubing
sections, one of said tubing sections comprising a seating nipple
adapted to receive a hold-down projection of the pump, one of said
tubing collars being disposed between an upper end of said seating
nipple and a lower end of the next upper tubing section, said one
tubing collar including an inner surface tapering from an upper
cross-section to a smaller lower cross-section to provide an
upwardly expanding volume for receiving accumulated debris as the
pump is raised relative to the well tubing.
2. A well tubing according to claim 1, wherein said inner surface
is of frusto-conical shape.
3. A well tubing according to claim 1, wherein said inner surface
is disposed between two internally threaded sections of said tubing
collar.
4. In combination, a well tubing and an insert pump,
said insert pump comprising a no-go ring, a hold-down projection
extending downwardly from said no-go ring, and seal means carried
on an outer surface of said hold-down projection, said well tubing
comprising a plurality of tubing sections interconnected by tubing
collars, said tubing collars having internal threading connected to
external threading on successively arranged ones of said tubing
sections, one of said tubing sections comprising a seating nipple
having an internal surface in which said hold-down projection is
disposed such that said sealing means seats sealingly against said
inner surface, one of said tubing collars being disposed between an
upper end of said seating nipple and a lower end of the next upper
tubing section, said one tubing collar including an inner surface
tapering from an upper cross-section to a smaller lower
cross-section to provide an upwardly expanding volume for receiving
accumulated debris as the pump is raised relative to said well
tubing.
5. A combination according to claim 4, wherein a distance from an
upper end of said no-go ring to a lower end of said next upper
tubing section being greater than a longest distance from an upper
end of said seating nipple to a lowermost end of said sealing
means.
6. A combination according to claim 5, wherein said sealing means
comprises a plurality of vertically spaced annular seals, said
longest distance defined between said upper end of said seating
nipple and the lowermost one of said annular seals.
7. A combination according to claim 4, wherein said inner surface
is frusto-conical.
8. A combination according to claim 4, wherein said lower
cross-section is substantially equal to an outer diameter of said
no-go ring.
9. A combination according to claim 4, wherein said inner surface
of said tubing collar is situated axially between two internally
threaded sections of said tubing collar.
10. A hollow tubing collar for use in a well tubing for making
threaded connection with an upper end of a seating nipple of the
well tubing, said tubing collar comprising upper and lower
internally threaded sections spaced apart in an axial direction of
said tubing collar, and an axial through-bore defined by an
internal surface which tapers from its upper cross-section located
adjacent said upper threaded section to its lower cross-section
located adjacent said lower threaded section, said lower
cross-section being smaller than said upper cross-section.
Description
BACKGROUND OF THE INVENTION
This invention relates to oil well production equipment and, in
particular, to artificial lift installations.
A common method of achieving artificial lift in an oil well
involves the use of an insert pump which is installed at a
prescribed depth within the production tubing. Depicted in FIG. 1
is a conventional pump 10 which has been lowered into a
conventional production tubing 12 by means of sucker rods (not
shown). The production tubing comprises a plurality of tube
segments 12A, 12B, 12C interconnected by tubing collars 14, 16. The
tube segment 12B constitutes a seating nipple which is adapted to
receive a hold-down projection 18 of the pump. The hold-down
projection, which is of cylindrical shape, carries a plurality of
elastic seal rings or cups 20 which seal against an inner bore 22
of the seating nipple 12B.
The pump further includes a no-go ring 24 fixed at the top of the
hold-down projection. The no-go ring 24 has an outer diameter which
is larger than the outer diameter of the pump barrel 25, and which
is appreciably larger than the diameter of the bore 22 of the
seating nipple to limit the downward travel of the pump by abutting
against the top of the seating nipple 12B.
The pump is installed by being lowered such that the hold-down
projection enters the seating nipple 12B, and the no-go ring 24
abuts the top of the seating nipple 12B, providing a positive
indication that the pump 10 is seated on the seating nipple. The
pump remains connected in that fashion during the period in which
it pumps fluid from the well. When it becomes necessary to remove
the pump from the well for replacement or repair, the pump is
pulled up by the sucker rods. Eventually the seal cups are pulled
from the seating nipple. This enables fluid in the tubing to
by-pass the seal cups and seek a hydraulic balance inside and
outside of the tubing. Thereafter, the pump is raised from the
tubing 12.
It sometimes occurs, however, that the pump becomes stuck within
the seating nipple 12B, requiring that the tubing be raised, at
considerable time and expense.
It is the belief of the present inventor that such sticking of the
pump results from the accumulation of debris such as sand and scale
S, for example, within an annular space 26 formed between a
cylindrical inner surface 27 of the tubing collar 14 and a
cylindrical outer surface of the pump, as depicted in FIG. 3. The
surface 27 is disposed between threaded sections 29, 31 of the
tubing collar 14. The accumulated debris moves upwardly with the
pump and becomes wedged within a restriction 30 formed between the
tubing 12A and the outer periphery of the pump, thereby inhibiting
further raising of the pump.
It would, therefore, be desirable to provide a tubing section which
enables the pump to be removed.
SUMMARY OF THE INVENTION
The present invention relates to the combination of well tubing and
an insert pump, as well as to the well tubing per se, and also to a
hollow tubing collar per se for use in the well tubing.
The insert pump comprises a no-go ring, a hold-down projection
extending downwardly from the no-go ring, and a seal carried on an
outer surface of the hold-down projection. The well tubing
comprises a plurality of tubing sections interconnected by tubing
collars. The tubing collars have internal threading connected to
external threading on successively arranged ones of the tubing
sections. One of the tubing sections comprises a seating nipple
having an internal surface in which the hold-down projection is
disposed so that the seal seats sealingly against the inner
surface. One of the tubing collars is disposed between an upper end
of the seating nipple and a lower end of the next upper tubing
section. That one tubing collar includes an inner surface tapering
from an upper cross section to a smaller lower cross-section to
provide an upwardly expanding volume for receiving accumulated
debris as the pump is raised relative to the well tubing.
Preferably, the inner surface of the one tubing collar is of
frusto-conical shape, and the smaller cross-section thereof is
substantially equal to the outer diameter of the no-go ring.
BRIEF DESCRIPTION OF THE DRAWINGS
The objects and advantages of the invention will become apparent
from the following detailed description of a preferred embodiment
thereof in connection with the accompanying drawings, in which like
numerals designate like elements,and in which:
FIG. 1 is longitudinal sectional view taken through a conventional
well tubing in which a conventional insert pump is installed;
FIG. 2 is a view similar to FIG. 1 wherein the well tubing includes
a tubing collar according to the present invention;
FIG. 3 is an enlarged fragmentary view of the conventional well
tubing and insert pump depicted in FIG. 1; and
FIG. 4 is a longitudinal sectional view taken though a tubing
collar according to the present invention.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION
Depicted in FIG. 2 is a an insert pump 10 according to the present
invention which has been lowered into a production tubing 12' by
means of sucker rods (not shown). The production tubing comprises a
plurality of conventional tube segments 12A, 12B, 12C
interconnected by tubing collars 14', 16, the latter being
conventional. The tube segment 12B constitutes a seating nipple
which is affixed at a lower end of the pump. The hold-down
projection 18, which is of cylindrical shape, carries a plurality
of elastic seal rings or cups 20 which seal against an inner bore
22 of the seating nipple of the tube segment 12B. The dimensions of
the hold-down projection 18 are standardized in the industry, and
the bore 22 is polished to a length sufficient to ensure that the
rings 20 engage a polished surface. The pump further includes a
no-go ring 24 fixed at the top of the hold-down projection. The
no-go ring 24 has an outer diameter which is larger than the outer
diameter of the pump barrel 25, and appreciably larger than the
diameter of the bore 22 of the seating nipple to limit the downward
travel of the pump by abutting against the seating nipple at the
upper end of the tube segment 12B.
When it becomes necessary to remove the pump from the well for
replacement or repair, the pump is pulled up by the sucker rods
until the seal cups are pulled from the seating nipple. This
enables fluid in the tubing to by-pass the seal cups and seek a
hydraulic balance inside and outside of the tubing. Then, the pump
is pulled through the tube segment 12A and is lifted to the
surface.
The tubing collar 14' is configured to resist the tendency for
debris, which may have accumulated in the space 26' between the
inner surface 27' of the tubing collar 14' and the outer periphery
of the pump 10, to become wedged within a restriction 30 formed
between the pump and the lower end of the next upper tubing section
12A.
In that regard, the inner surface 27' of the tubing collar 14',
which lies between two axially spaced threaded sections 29', 31' is
of frusto-conical shape so as to taper from a small lower diameter
to a larger upper diameter. Preferably, the lower diameter is
substantially the same as the outer diameter of the no-go ring.
During a pumping operation, debris may accumulate within the space
26' formed between the inner surface of the tubing collar and the
outer periphery of the pump. However, even if that debris tends to
be raised along with the pump as the pump is being removed, the
tapering nature of the surface provides a space of continuously
expanding volume for receiving the debris, so that the debris will
be less likely to become wedged in a manner preventing the upward
pump travel.
Once all of the seal cups 20 have exited from the seating nipple
12B, the seal between the pump and well tubing is broken, thereby
enabling fluid within the tubing to flow downwardly past the seal
cups to wash away the debris. The upward travel of the pump can
then continue unhindered.
The length of the inner surface 27' is preferably designed to be
great enough to ensure that the sealing cups 20 will have left the
bore 22 by the time that the no-go ring 24 reaches the lower end of
the tubing section 12A. That is, the axial distance from the top
end of the no-go ring to the lower end of the tubing section 12A is
greater than the axial distance between the lowermost sealing cup
and the upper end of the seating nipple of the tube segment 12B. As
a consequence, it is ensured that all of the seal cups 20 will have
exited the seating nipple before the no-go ring 24 reaches the
restriction 30. This aspect of the surface 27' is particularly
advantageous in cases where the outer diameter of the no-go ring 24
exceeds the outer diameter of the pump barrel 25.
Although the present invention has been described in connection
with a preferred embodiment thereof, it will be appreciated by
those skilled in the art that additions, deletions, modifications,
and substitutions may be made without departing from the spirit and
scope of the invention as defined in the appended claims.
* * * * *